Random access method, radio communication terminal device, receiving method, and base station apparatus

ABSTRACT

Random access technology is provided for establishing an individual channel between a radio communication terminal device and a base station device in a short time and a radio communication terminal device executing the random access method. A RACH sub-channel allocation unit allocates a transmission packet input from a replication unit to an arbitrary sub-carrier at the RACH arbitrary time slot at random. An allocation unit judges whether an overlap is generated in the allocation result obtained by the RACH sub-channel allocation unit.

PRIORITY APPLICATIONS

This is a continuation application of application Ser. No. 14/724,929,filed May 29, 2015, which is a continuation of application Ser. No.14/283,525, filed May 21, 2014 now U.S. Pat. No. 9,060,356, which is acontinuation of application Ser. No. 13/158,014, filed Jun. 10, 2011,now U.S. Pat. No. 8,761,131, which is a continuation application ofapplication Ser. No. 12/965,641, filed Dec. 10, 2010, now U.S. Pat. No.8,000,295, which is a continuation application of application Ser. No.10/591,712 filed Sep. 6, 2006, now U.S. Pat. No. 7,873,000, which is anational stage of PCT/JP2005/003329 filed Feb. 28, 2005, which is basedon Japanese Application No. 2004-065625 filed Mar. 9, 2004, the entirecontents of each which are incorporated by reference herein.

TECHNICAL FIELD

The present invention relates to a random access method in a radiocommunication system composed of a plurality of radio communicationterminal apparatuses and base station apparatuses, and a radiocommunication terminal apparatus of the random access method.

BACKGROUND

Conventionally, in a radio communication system by a cellular scheme,when a radio communication terminal apparatus starts or restartscommunication, an individual channel between the radio communicationterminal apparatus and the base station apparatus is not establishedyet, and the radio communication terminal apparatus is thereforedesigned to attempt an access to the base station apparatus using arandom access channel (hereinafter “RACH”: Random Access Channel). Forexample, in the radio communication system by a W-CDMA scheme, a slottedALOHA scheme is adopted. When each of a plurality of radio communicationterminal apparatuses start or restart communication, access to the basestation apparatus is attempted at an arbitrary timing out of starttiming candidates (RACH subchannel). If there is no response from thebase station apparatus within predetermined time from the access time,the access is determined failed, and access to the base stationapparatus is attempted again (see, for example, Non-Patent Document 1).

Further, in the radio communication system by a multi-carriertransmission scheme, a technology is known in which when transmissionpacket is transmitted to the base station apparatus by RACH forestablishing an individual channel, the radio communication terminalapparatus selects slot (timing) and subcarrier (frequency) of RACH andspreading code based on certain conditions, spreads the transmissionpacket by the selected spreading code, and then transmits the packet tothe base station apparatus at the selected tuning and frequency (see,for example, Patent Document 1). Furthermore, in a technology disclosedin Patent Document 1, a radio communication terminal apparatus attemptsan access to the base station apparatus, and if there is no responsefrom the base station apparatus within predetermined time from theaccess time, the radio communication terminal apparatus attempts anaccess to the base station apparatus again.

Patent Document 1: Japanese Patent Application Laid-Open No. 2001-268051

Non-Patent Document 1: Keiji Tachikawa (ed.), “W-CDMA MobileCommunication Scheme,” Maruzen Co., Ltd., p. 45, Jun. 25, 2001

DISCLOSURE

However, in technologies disclosed in Patent Document 1 and Non-PatentDocument 1, a plurality of radio communication terminal apparatusesattempt an access to the base station apparatus by RACH and access tothe base station apparatus is attempted again after determining successor failure for establishing individual channels so that a case may occurwhen establishing the individual channel after the first access to thebase station apparatus may require time. Furthermore, the number oftransmission packets transmitted by RACH increases as the number ofradio communication terminal apparatuses belonging to the same cellincreases so that the likelihood of collision of transmission packetsbecomes high and establishing the individual channels requires longertime. For this reason, with the conventional technology, the problems ofdeterioration of communication quality and non-accessible state forcommunication and the like are made more likely to occur in the radiocommunication terminal apparatus designed to plan a service demanding aQoS (Quality of Service) delay requirement.

It is therefore an object of the present invention to provide a randomaccess method for establishing an individual channel between a radiocommunication terminal apparatus and a base station apparatus in a shorttime, and a radio communication terminal apparatus for operating thisrandom access method.

A Random access method according to the present invention includes aduplication step of duplicating a transmission packet, an assignmentstep of assigning each of a plurality of duplicated transmission packetsto a random access channel, and a transmission step of transmitting theplurality of the transmission packets in accordance with an assignmentresult in the assignment step.

According to this method, the radio communication terminal apparatusassigns and transmits a plurality of transmission packets to the basestation apparatus by RACH so that, even when many radio communicationterminal apparatuses belong to the same cell, the likelihood becomeshigh that, one of the plurality of transmission packets is received bythe base station apparatus without colliding with transmission packetstransmitted from other radio communication terminal apparatuses. As aresult, according to this method, the radio communication terminalapparatus transmits the duplicated transmission packets to RACH withoutwaiting for a response from the base station apparatus to confirmwhether or not the transmission packets transmitted to RACH are receivedat the base station apparatus, thereby establishing an individualchannel to the base station apparatus in a short time.

The random access method according to the present invention includes, inthe above-mentioned invention, a determination step of determining thenumber of duplications of the transmission packet in the duplicationstep according to a priority of service planned after communication isstarted.

According to this method, in addition to the effect of the invention,the number of transmission packets transmitted to RACH by the radiocommunication terminal apparatus is determined according to kinds ofservices planned after the individual channel is established so that,out of the plurality of the radio communication terminal apparatusesbelonging to the same cell, one with higher urgency is more likely toestablish the individual channel. As a result, according to this method,the problems of deterioration of communication quality, non-accessiblestate for communication and the like are made less likely to occur inthe plurality of the whole radio communication terminal apparatusesbelonging to the same cell.

The random access method according to the present invention includes, inthe above-mentioned invention, a determination step of determining thenumber of duplications of the transmission packet in the duplicationstep according to the number of retransmissions of the transmissionpacket.

According to this method, in addition to the effect of the invention,the number of duplications of the transmission packet increasesaccording to the number of retransmissions of transmission packets sothat, out of the plurality of the radio communication terminalapparatuses belonging to the same cell, one with higher urgency is morelikely to establish the individual channel. As a result, according tothis method, the problems of deterioration of communication quality,non-accessible state for communication and the like are made less likelyto occur in the plurality of the whole radio communication terminalapparatuses belonging to the same cell.

The random access method according to the present invention includes, inthe above-mentioned invention, a determination step of determining thenumber of duplications of the transmission packet in the duplicationstep according to the number of the radio communication terminalapparatuses belonging to the same cell and using said random accesschannel.

According to this method, in addition to the effect of the invention, ifthe number of the radio communication terminal apparatuses belonging tothe same cell increases, radio communication terminal apparatuses makeless the number of the duplications of the transmission packet so thatit is possible to reduce the likelihood of collision of transmissionpackets. As a result, according to this method, the problems ofdeterioration of communication quality, non-accessible state forcommunication and the like are made less likely to occur in theplurality of the whole radio communication terminal apparatusesbelonging to the same cell.

With the random access method according to the present invention, in theassignment step of the above-mentioned invention, each of the pluralityof duplicated transmission packets are assigned to one of time slots inthe random access channel.

With the random access method according to the present invention, in theassignment step of the above-mentioned invention, each of the pluralityof duplicated transmission packets are assigned to one of subcarriers inthe random access channel.

According to these methods, in addition to the effect of the invention,the radio communication terminal apparatus assigns the plurality oftransmission packets randomly to one of time slots and subcarriers ofRACH so that it is possible to reduce load of the signal processingnecessary for the assignment of transmission packets in the radiocommunication terminal apparatus.

With the random access method according to the present invention, in theassignment step of the above-mentioned invention, each of the pluralityof duplicated transmission packets are assigned to one of time slots andone of subcarriers in the random access channel.

According to this method, in addition to the effect of the invention,the radio communication terminal apparatus assigns the plurality oftransmission packets randomly to time slots and subcarriers of RACH sothat, even when many radio communication terminal apparatuses belong tothe same cell, it is possible to reduce the likelihood of collision ofthe transmission packets.

With the random access method according to the present invention, in theassignment step of the above-mentioned invention, each of the pluralityof duplicated transmission packets are assigned to one of spreadingcodes in the random access channel.

According to this method, in addition to the effect of the invention,the plurality of radio communication terminal apparatuses spread andtransmit the transmission packets to the base station apparatus usingthe spreading codes selected randomly so that, even when many radiocommunication terminal apparatuses belong to the same cell, it ispossible to reduce the likelihood of collision of transmission packets.

A radio communication terminal apparatus according to the presentinvention adopts a configuration having: a duplication section thatduplicates a transmission packet; an assignment section that assignseach of the plurality of duplicated transmission packets to a randomaccess channel; and a transmission section that transmits the pluralityof transmission packets in accordance with an assignment result in theassignment section.

According to this configuration, the radio communication terminalapparatus assigns the plurality of the duplicated transmission packetsrandomly to RACH and transmits the transmission packets to the basestation apparatus so that, even when many radio communication terminalapparatuses belong to the same cell, the likelihood becomes high that,the plurality of transmission packets are received by the base stationapparatus without colliding with transmission packets transmitted fromother radio communication terminal apparatuses. As a result, accordingto this configuration, the radio communication terminal apparatustransmits the duplicated transmission packets to RACH without waitingfor a response from the base station to confirm whether or not thetransmission packets transmitted to RACH are received at the basestation, thereby establishing an individual channel to the base stationapparatus in a short time.

According to the present invention, the plurality of the radiocommunication terminal apparatuses assign the plurality of theduplicated transmission packets randomly to RACH and transmits thetransmission packets to the base station apparatus so that, even whenmany radio communication terminal apparatuses belong to the same cell,the likelihood becomes high that, the plurality of transmission packetsare received by the base station apparatus without colliding withtransmission packets transmitted from other radio communication terminalapparatuses. As a result, according to this invention, the radiocommunication terminal apparatus transmits the duplicated transmissionpackets to RACH without waiting for a response from the base stationapparatus to confirm whether or not the transmission packets transmittedto RACH are received at the base station, thereby establishing anindividual channel to the base station in a short time.

BRIEF DESCRIPTION OF DRAWINGS

FIG. 1 shows a configuration of a radio communication terminal systemusing a random access method according to Embodiment 1 of the presentinvention;

FIG. 2 is a block diagram showing a configuration of a radiocommunication terminal apparatus according to Embodiment 1 of thepresent invention;

FIG. 3 is a flow chart explaining a random access method according toEmbodiment 1 of the present invention;

FIG. 4A shows an assignment of a transmission packet to RACH accordingto Embodiment 1;

FIG. 4B shows an assignment of a transmission packet to RACH accordingto Embodiment 1;

FIG. 4C shows an assignment of a transmission packet to RACH accordingto Embodiment 1;

FIG. 4D shows an assignment of a transmission packet to RACH accordingto Embodiment 1;

FIG. 5A shows an assignment of a transmission packet to RACH accordingto Embodiment 1;

FIG. 5B shows an assignment of a transmission packet to RACH accordingto Embodiment 1;

FIG. 5C shows an assignment of a transmission packet to RACH accordingto Embodiment 1;

FIG. 5D shows an assignment of a transmission packet to RACH accordingto Embodiment 1;

FIG. 5E shows an assignment of a transmission packet to RACH accordingto Embodiment 1;

FIG. 6 is a block diagram showing a configuration of a radiocommunication terminal apparatus according to Embodiment 2 of thepresent invention;

FIG. 7 is a flow chart explaining a random access method according toEmbodiment 2 of the present invention;

FIG. 8 is a block diagram showing a configuration of a radiocommunication terminal apparatus according to Embodiment 3 of thepresent invention;

FIG. 9 is a flow chart explaining a random access method according toEmbodiment 3 of the present invention;

FIG. 10 is a block diagram showing a configuration of a radiocommunication terminal apparatus according to Embodiment 4 of thepresent invention;

FIG. 11 is a flow chart explaining a random access method according toEmbodiment 4 of the present invention;

FIG. 12A shows a correlation between a priority, the number of the radiocommunication terminal apparatuses belonging to the same cell, and thenumber of duplications of a transmission packet according to Embodiment4; and

FIG. 12B shows a correlation between a priority, the number of the radiocommunication terminal apparatuses belonging to the same cell, and thenumber of duplications of a transmission packet according to Embodiment4.

DETAILED DESCRIPTION Example Embodiment 1

FIG. 1 shows a schematic configuration of a radio communication systemcomposed of four radio communication terminal apparatuses 200-1 to 200-4and base station apparatus 100 that establish individual channels usinga random access method according to Embodiment 1 of the presentinvention. In FIG. 1, a communication area of this radio communicationsystem is indicated as “cell A.” Furthermore, an OFDM (OrthogonalFrequency Division Multiplexing) signal is subjected to packet exchangein cell A of FIG. 1. In addition, the configurations and operations ofthe radio communication terminal apparatuses 200-1 to 200-4 will beexplained below, but the radio communication terminal apparatuses 200-1to 200-4 refer to the same configuration and the same function so thatthe branch numbers may be omitted when explanations of the function andthe like are made entirely.

FIG. 2 is a block diagram showing a configuration of radio communicationterminal apparatus 200. Radio communication terminal apparatus 200includes transmission packet generating section 201, duplication section202, assignment section 210, packet multiplexing section 221, radiotransmission section 222 and antenna element 223. Furthermore,assignment section 210 includes RACH subchannel assigning sections 211-1to 211-c. In addition, “c” is an arbitrary natural number of two orgreater.

Transmission packet generating section 201 generates transmission packetincluding information of radio communication terminal apparatus 200necessary for establishing an individual channel to base stationapparatus 100 when radio communication terminal apparatus 200 is startedor recovered from the idol state, and inputs the generated transmissionpacket to duplication section 202.

Duplication section 202 duplicates the transmission packet input fromtransmission packet generating section 201, and inputs c duplicatedtransmission packets to RACH subchannel assigning sections 211-1 to211-c, respectively.

RACH subchannel assigning section 211 assigns the transmission packetsinput from duplication section 202 randomly to arbitrary subcarrierswith arbitrary RACH time slots. Assignment section 210 compares theassignment results of RACH subchannel assigning sections 211-1 to 211-ceach other, and when transmission packets are assigned to the samesubcarrier with the same time slot with overlap, assignment section 210instructs one of RACH subchannel assigning sections 211 to performassignment again. Assignment section 210 then instructs RACH subchannelassigning sections 211-1 to 211-c to input transmission packets topacket multiplexing section 221 with the subcarriers of assigned timeslots after confirming that time slots and subcarriers assigned by RACHsubchannel assigning sections 211-1 to 211-c are not overlapped. RACHsubchannel assigning sections 211-1 to 211-c input transmission packetsat predetermined timing and frequency to packet multiplexing section 221in accordance with instructions from assignment section 210.

Packet multiplexing section 221 multiplexes transmission packets inputfrom RACH subchannel assigning sections 211-1 to 211-c and inputsmultiplexed transmission packets to radio transmission section 222.

Radio transmission section 222 is composed of S/P converter, IFFTapparatus, P/S converter, guard interval insertion apparatus, bandpassfilter, D/A converter, low noise amplifier or the like, and aftergenerating an OFDM (Orthogonal Frequency Division Multiplexing) signalfrom the transmission packet input from packet multiplexing section 221,radio transmission section 222 transmits the generated OFDM signal byradio to base station apparatus 100 through antenna element 223.

Next, the operations of radio communication terminal apparatus 200 willbe explained using FIG. 3. FIG. 3 is a flow chart showing steps of arandom access method according to this embodiment.

First, in step ST310, duplication section 202 duplicates c transmissionpackets input from transmission packet generating section 201.

Next, in step ST320, RACH subchannel assigning sections 211-1 to 211-cassign the transmission packets input from duplication section 202randomly to arbitrary subcarriers at arbitrary time slots of RACH.

Next, in step ST330, assignment section 210 determines whether or notassignment results by RACH subchannel assigning sections 211-1 to 211-care overlapped. When assignment section 210 determines assignmentresults by RACH subchannel assigning section 211 are overlapped in stepST330, assignment section 210 makes one of RACH subchannel assigningsections 211 which has caused the overlap perform the assignment of stepST320 again. On the other hand, in step ST330, when assignment section210 determines assignment results by RACH subchannel assigning section211 are not overlapped, step ST340 is executed.

Next, in step ST340, radio transmission section 222 generates an OFDMsignal from the transmission packet input from packet multiplexingsection 221, and transmits the generated OFDM signal by radio to basestation apparatus 100 by RACH through antenna element 223.

FIGS. 4A to 4D and FIGS. 5A to 5E show specific aspect of assigning atransmission packet to the arbitrary subcarriers at arbitrary time slotsof RACH by the random access method according to this embodiment. Inthis embodiment, RACH subchannel assigning section 211 is taken toprocess five subcarriers (SC) and five time slots (TS) as a unit of RACHand assigns transmission packets randomly within this one unit. As canbe seen in FIG. 4A, for example, transmission packets (RACH accesssignals) are continuously transmitted using five consecutive time slotsTS1, TS2, TS3, TS4, TS5 and are consecutive in the time domain.

FIG. 4A shows an assignment of transmission packets to RACH in radiocommunication terminal apparatus 200-1, and FIG. 4B to FIG. 4D showradio communication terminal apparatuses 200-2 to 200-4, respectively.FIG. 4A and FIG. 4D show an aspect of randomly assigning transmissionpackets to one of time slots and to one of subcarriers of RACH, and FIG.4B to one of subcarriers by all time slots of RACH, and FIG. 4C to oneof time slots in SC3 of RACH.

FIGS. 5A to 5E show transmission conditions of radio communicationterminal apparatuses 200-1 to 200-4 about SC1 to SC5 in timings of TS1to TS5, in the case that radio communication terminal apparatuses 200-1to 200-4 transmit transmission packets by the assignment aspects shownin FIGS. 4A to 4D. FIG. 5A shows a transmission condition in TS1, FIG.5B in TS2, FIG. 5C in TS3, FIG. 5D in TS4 and FIG. 5E in TS5,respectively. FIGS. 5A to 5E append “x” to all colliding transmissionpackets and “o” to transmission packets first received at base stationapparatus 100, per radio communication terminal apparatuses 200-1 to200-4.

As shown in FIGS. 5A to 5E, individual channels can be established tobase station apparatus 100, at a timing of TS 1 in radio communicationterminal apparatus 200-1, at a timing of TS3 in radio communicationterminal apparatus 200-2, at a timing of TS5 in radio communicationterminal apparatus 200-3 and at a timing of TS4 in radio communicationterminal apparatus 200-4, respectively.

In this way, according to this embodiment, radio communication terminalapparatus 200 assigns a plurality of duplicated transmission packets toRACH randomly in RACH subchannel assigning sections 211-1 to 211-c, andtransmits the transmission packets at the assigned time slots andsubcarriers without waiting for a response from base station apparatus100 to the first transmission packets, thereby establishing anindividual channel to base station apparatus 100 in a short time.

Furthermore, a plurality of transmission packets are assigned to timeslots of RACH randomly only according to radio communication terminalapparatus 200-2 of this embodiment, and to subcarrier of RACH onlyaccording to radio communication terminal apparatus 200-3 so that it ispossible to reduce load of signal processing in RACH subchannelassigning section 211 necessary for the assignment of transmissionpackets compared to the case that the plurality of transmission packetsare assigned to time slots and subcarriers of RACH randomly.

Moreover, according to radio communication terminal apparatus 200-1 or200-4 of this embodiment, RACH subchannel assigning section 211 assignsa plurality of transmission packets to one of time slots of RACH andalso to one of subcarriers of RACH randomly so that, even when manyradio communication terminal apparatuses 200 belong to the same cell, itis possible to reduce the likelihood of collision of transmissionpackets in RACH.

In addition, the following applications and changes may be possible tothe random access method and radio communication terminal apparatus 200according to this embodiment.

In this embodiment, a case has been described where a plurality of radiocommunication terminal apparatuses 200 assign transmission packetsrandomly to time slots and subcarriers of RACH, but the presentinvention is not limited to this, and, for example, it is equallypossible for a plurality of radio communication terminal apparatuses 200to transmit not OFDM but packet signals of a single carrier by radiocommunication, and assign those packet signals randomly to the arbitrarytime slots of RACH.

Furthermore, in this embodiment, a case has been described where radiocommunication terminal apparatus 200 assigns randomly and transmitstransmission packets to time slots and subcarriers of RACH, but thepresent invention is not limited to this, and, for example, it ispossible for radio communication terminal apparatus 200 to selectspreading codes randomly instead of time slots and subcarriers of RACH,and also perform code division of the transmission packets using theselected spreading codes. Furthermore, it is possible for radiocommunication terminal apparatus 200 to assign transmission packetsrandomly to RACH subchannel where time slots, subcarriers and spreadingcodes are setting elements. As a result, even when many radiocommunication terminal apparatuses 200 belong to the same cell, it ispossible to further reduce the likelihood of collision of transmissionpackets in RACH.

Example Embodiment 2

FIG. 6 is a block diagram showing a configuration of radio communicationterminal apparatus 600 according to Embodiment 2 of the presentinvention. Radio communication terminal apparatus 600 further includespriority determining section 601 and number-of-duplications determiningsection 602 in radio communication terminal apparatus 200 explained inEmbodiment 1. Therefore, radio communication terminal apparatus 600includes many components to show the same function as in the componentsof radio communication terminal apparatus 200, so that such componentsare assigned the same reference numerals as in the components of radiocommunication terminal apparatus 200, and explanations thereof will beomitted.

Priority determining section 601 determines a priority according tokinds of services planned by radio communication terminal apparatus 600after communication with base station apparatus 100 is started. Forexample, in call services and video streaming services, since allowabledelay time is short (QoS delay requirement is demanding), prioritydetermining section 601 determines that high priority is necessary inradio communication terminal apparatus 600 scheduled to plan suchservice. Priority determining section 601 then inputs information of thedetermined priority to number-of-duplications determining section 602.

Number-of-duplications determining section 602 compares priorityinformation input from priority determining section 601 with aconversion table provided in advance, determines the number ofduplications corresponding to the priority and inputs information of,the determined number of duplications to duplication section 202.

Next, the operations of radio communication terminal apparatus 600 willbe explained using FIG. 7. FIG. 7 is a flow chart explaining steps ofthe random access method according to Embodiment 2 of the presentinvention.

First, in step ST710, priority determining section 601 determines apriority of radio communication terminal apparatus 600 based on QoSdelay requirement information input from control section or the like(not shown).

Subsequently, in step ST720, number-of-duplications determining section602 determines the number of duplications of transmission packetsaccording to the priority determined in step ST710, and inputsinformation of the number of duplications to duplication section 202.

Then, steps ST310 to 340 in Embodiment 1 are to be sequentiallyexecuted.

Here, an example of the conversion table held in number-of-duplicationsdetermining section 602 will be shown below in “Table 1.” Thisconversion table is made such that α=1, based on c=αxp . . . (1) {c isthe number of duplications, α is constant and p is the priority}.

TABLE 1 Priority: Number of duplications 5:5 4:4 3:3 2:2 1:1

In this way, according to the random access method of this embodiment,the number of duplications of transmission packet in duplication section202 are determined according to kinds of services to be planned after anindividual channel is established, and as QoS delay requirement out of aplurality radio communication terminal apparatuses 600 becomes moredemanding so that it is possible to establish the individual channel tobase station apparatus 100 in a short time. As a result, according tothe random access method according to this embodiment, the problems ofdeterioration of communication quality, non-accessible state forcommunication and the like are made less likely to occur in theplurality of the whole radio communication terminal apparatuses 600belonging to the same cell.

Example Embodiment 3

FIG. 8 is a block diagram showing a configuration of radio communicationterminal apparatus 800 according to Embodiment 3 of the presentinvention. Radio communication terminal apparatus 800 further includesnumber-of-duplications determining section 802 in radio communicationterminal apparatus 200 explained in Embodiment 1. Radio communicationterminal apparatus 800 includes many components to show the samefunction as in the components of radio communication terminal apparatus200 so that such components are assigned the same reference numerals asin the components of radio communication terminal apparatus 200, andexplanations thereof will be omitted.

Number-of-duplications determining section 802 compares information ofthe number of retransmissions input from control section or the like(not shown) with a conversion table provided in advance, determines thenumber of duplications corresponding to the number of retransmissionsand inputs information of the determined number of duplications toduplication section 202. In addition, “the number of retransmissions” inthis embodiment is incremented every time all TS1 to TS5 shown in eitherof FIGS. 4A to 4D are transmitted.

Next, the operations of radio communication terminal apparatus 800 willbe explained using FIG. 9. FIG. 9 is a flow chart explaining steps of arandom access method according to this embodiment.

First, in step ST910, number-of-duplications determining section 802compares the number of retransmissions input with the conversion tableprovided in advance, determines the number of duplications of thetransmission packet and inputs information of the determined number ofduplications to duplication section 202.

Then, steps ST310 to ST340 in Embodiment 1 are to be sequentiallyexecuted.

Here, an example of a conversion table held in number-of-duplicationsdetermining section 802 will be shown below in “Table 2.” Thisconversion table is made such that β=1, based on c=Fxβ . . . (1) {c isthe number of duplications, F is the number of retransmissions and β isconstant}.

TABLE 2 Number of retransmissions: Number of duplications 5:6 4:5 3:42:3 1:2

In this way, according to the random access method of this embodiment,the number of transmission packets transmitted from radio communicationterminal 800 to base station apparatus 100 by RACH increases accordingto the number of retransmissions so that, out of a plurality of radiocommunication terminal apparatuses 800 belonging to the same cell, onewith higher urgency is more likely to establish the individual channelto base station apparatus 100 in a short time. As a result, according tothe random access method of this embodiment, the problems ofdeterioration of communication quality, non-accessible state forcommunication and the like are made less likely to occur in theplurality of the whole radio communication terminal apparatuses 800belonging to the same cell.

Example Embodiment 4

FIG. 10 is a block diagram showing a configuration of radiocommunication terminal apparatus 1000 according to Embodiment 4 of thepresent invention. Radio communication terminal apparatus 1000 furtherincludes radio reception section 1001, control information extractingsection 1002 and number-of-duplications determining section 1003 inradio communication terminal apparatus 200 explained in Embodiment 1.Radio communication terminal apparatus 1000 includes many components toshow the same function as in the components of radio communicationterminal apparatus 200 so that such components are assigned the samereference numerals as in the components of radio communication terminalapparatus 200, and explanations thereof will be omitted.

Radio reception apparatus 1001 includes bandpass filter, A/D converter,low noise amplifier, guard interval removal apparatus, S/P converter,FFT apparatus, P/S converter or the like, and acquires an OFDM signal tonotify the number of radio communication terminal apparatus 1000 whichbelong to cell A transmitted regularly from base station terminal 100through antenna element 223, and after predetermined reception signalproceeding to the OFDM signal is performed, radio reception section 1001inputs the OFDM signal to control information extracting section 1002.

Control information extracting section 1002 extracts information of thenumber of radio communication terminal apparatuses 1000 belonging tocell A out of the reception signal input from radio reception section1001, and inputs the extracted control information tonumber-of-duplications determining section 1003.

Number-of-duplications determining section 1003 compares controlinformation input from control information extracting section 1002 withthe conversion table provided in advance, determines the number ofduplications corresponding to the control information and inputs theinformation of the determined number of duplications to duplicationsection 202.

Next, the operations of radio communication terminal apparatus 1000 willbe explained using FIG. 11. FIG. 11 is a flow chart explaining steps fora random access method according to this embodiment.

First, in step ST1110, control information extracting section 1002extracts control information from reception signal input from radioreception section 1001.

Then, in step ST1120, number-of-duplication determining section 1003learns the number of radio communication terminal apparatuses 1000belonging to cell A based on control information and determines thenumber of duplications corresponding to this number with reference tothe conversion table provided in advance.

Steps ST310 to ST340 in Embodiment 1 are to be sequentially executed.

Here, an example of the conversion table held in number-of-duplicationsdetermining section 1003 will be shown below in “Table 3.” In table 3,RACH subchannel assigning section 211 is taken to process a total of1000 RACH subchannels composed of 10 time slots and 100 subcarriers pertime slot as a RACH unit, assign 100 transmission packets at maximum inone unit and furthermore, radio communication terminal apparatus 1000belongs to priorities 1 to 5.

TABLE 3 Priority/Number of duplications (number ofterminals)/(20):(35):(100) 5/7(4):5(7):1(20) 4/6(4):4(7):1(20)3/5(4):3(7):1(20) 2/4(4):2(7):1(20) 1/1(4):1(7):1(20) Sum of the numberof duplications: 92:98:100

Furthermore, in FIG. 12A, correlation between the number of radiocommunication terminal apparatuses 1000 belonging to cell A and thenumber of duplications about priority 5 in this embodiment is shown.Also, in FIG. 12B, correlation between the number of radio communicationterminal apparatuses 1000 belonging to cell A and the number ofduplications about priority 3 in this embodiment is shown. As shown inFIG. 12A and FIG. 12B, this embodiment is set such that the number ofduplications of transmission packet in duplication section 202 decreaseswith increase of the number of radio communication terminal apparatuses1000 belonging to the same cell.

Therefore, according to the random access method of this embodiment, asthe number of radio communication terminal apparatuses 1000 belonging tothe same cell increases, the number of transmission packets transmittedby radio communication terminal apparatuses 1000 decreases so that it ispossible to reduce the likelihood of collision of transmission packetsat RACH in the same cell. As a result, according to the random accessmethod according to this embodiment, the problems of deterioration ofcommunication quality, non-accessible state for communication and thelike are made less likely to occur in the plurality of the whole radiocommunication terminal apparatuses 1000 belonging to the same cell.

In addition, although in the above embodiments, a case has beendescribed where the duplicated transmission packets are multiplexed andtransmitted in subcarriers or time slots, when, for example, otherresources such as radio communication terminal apparatus 200 include aplurality of transmission antennas, it is possible to multiplex andtransmit the duplicated transmission packets in spatial resources suchas transmission antenna and directivity pattern, and spreading codes inCDMA system.

In addition, function blocks used in the explanations of the aboveembodiments are typically implemented as LSI constituted by anintegrated circuit. These may be individual chips or partially ortotally contained on a single cup.

“LSI” is adopted here but this may also be referred to as “IC,” “systemLSI,” “super LSI,” or “ultra LSI” depending on differing extents ofintegration.

Further, the method of circuit integration is not limited to LSI's, andimplementation using dedicated circuitry or general purpose processorsis also possible. After LSI manufacture, utilization of an FPGA (FieldProgrammable Gate Array) or a reconfigurable processor where connectionsand settings of circuit cells within an LSI can be reconfigured is alsopossible.

Further, if integrated circuit technology comes out to replace LSI's asa result of the advancement of semiconductor technology or a derivativeother technology, it is naturally also possible to carry out functionblock integration using this technology. Application in biotechnology isalso possible.

The present application is based on Japanese Patent Application No.2004-065625 filed on Mar. 9, 2004, the entire content of which isexpressively incorporated by reference herein.

INDUSTRIAL APPLICABILITY

The random access method and radio communication terminal apparatusaccording to the present invention provides an advantage of establishingan individual channel to the base station in a short time, and iseffective for using in the radio communication system and the like withservice demanding QoS delay requirement planned.

1. A terminal apparatus comprising: a receiver configured to receive control information transmitted from a base station apparatus; signal generating circuitry configured to generate, based on received information from the base station, a random access signal requesting service from the base station apparatus and including a number of duplicated random access sequences, where the number of duplicated random access sequences is based on the control information received in advance from the base station; and a transmitter configured to transmit the random access signal, from the terminal apparatus to the base station apparatus over a random access channel, without waiting for a response from the base station apparatus to confirm whether either of the random access sequences of bits has been received at the base station apparatus.
 2. The terminal apparatus in claim 1, wherein the control information indicates a number of terminals belonging to a cell associated with the base station.
 3. The terminal apparatus in claim 2, wherein the signal generating circuitry is configured to determine the number of terminals belonging to a cell from the control information.
 4. The terminal apparatus in claim 2, wherein as the number of terminals belonging to the cell increases, the number of duplicated random access sequences decreases.
 5. The terminal apparatus in claim 1, wherein the duplicated random access sequences includes a random access sequence repeated successively in a time domain.
 6. The terminal apparatus in claim 1, wherein the transmitted random access signal includes the random access sequence of bits in one time slot and the duplicated random access sequence of bits in a second, different time slot.
 7. The terminal apparatus in claim 1, wherein the random access channel includes one or more of a time slot, frequency, or spreading code.
 8. The terminal apparatus in claim 1, wherein the random access sequence of bits and the repeated random access sequence of bits are consecutive in the time domain.
 9. The terminal apparatus in claim 1, wherein the transmitter is configured to transmit the random access signal on at least two consecutive time slots.
 10. The terminal apparatus in claim 1, wherein the number of duplicated random access sequences depends on a priority associated with the terminal apparatus.
 11. A method implemented in a terminal comprising: receiving control information transmitted from a base station apparatus; generating, based on received information from the base station, a random access signal requesting service from the base station apparatus and including a number of duplicated random access sequences, where the number of duplicated random access sequences is based on the control information received in advance from the base station; and transmitting the random access signal, from the terminal apparatus to the base station apparatus over a random access channel, without waiting for a response from the base station apparatus to confirm whether either of the random access sequences of bits has been received at the base station apparatus.
 12. The method in claim 11, wherein the control information indicates a number of terminals belonging to a cell associated with the base station.
 13. The method in claim 12, further comprising determining the number of terminals belonging to a cell from the control information.
 14. The method in claim 12, wherein as the number of terminals belonging to the cell increases, the number of duplicated random access sequences decreases.
 15. The method in claim 11, wherein the duplicated random access sequences includes a random access sequence repeated successively in a time domain.
 16. The method in claim 11, wherein the transmitted random access signal includes the random access sequence of bits in one time slot and a duplicated random access sequence of bits in a second, different time slot.
 17. The method in claim 11, wherein the random access channel is associated with radio resources, the method further comprising transmitting the random access signal using a radio resource selected at random from radio resource candidates.
 18. The method in claim 11, wherein the random access sequence of bits and the repeated random access sequence of bits are consecutive in the time domain.
 19. The method in claim 11, further comprising transmitting the random access signal on at least two consecutive time slots.
 20. The method in claim 11, wherein the number of duplicated random access sequences also depends on a priority associated with the terminal apparatus. 